Servovalve

Abstract

There is provided an apparatus comprising a torque motor comprising a spring, armature, flapper assembly (“SAFA”), a body, wherein the spring, armature, flapper assembly is mounted onto the body, and a cap enclosing the spring, armature, flapper assembly. One or more cooling passages are provided within the body and are configured to receive cooling air and direct the cooling air onto the spring, armature, flapper assembly of the torque motor.

The invention claimed is: 
     
       1. A method of cooling a torque motor comprising a spring, armature, flapper assembly (SAFA) comprising an armature ( 50 ) configured to pivot about its center to cause a lower end of a flapper of the assembly to move left and right, the method comprising:
 locating the SAFA on a body; 
 locating a cap over the body so as to at least partially enclose the SAFA; and 
 providing one or more cooling passages within the body, wherein each cooling passage is configured to direct a fluid at least partially onto the SAFA; 
 wherein the body comprises a portion configured to receive the flapper of the SAFA, and the one or more cooling passages are configured to direct the fluid at least partially onto the portion configured to receive the flapper of the SAFA; 
 wherein the torque motor further comprises:
 a pole piece; 
 wherein each of the one or more cooling passages is configured to direct the fluid through an aperture formed in the center of the pole piece; 
 
 wherein each cooling passage comprises a central axis (X), and the central axis (X) of each cooling passage extends through the aperture of the pole piece. 
 
     
     
       2. The method as claimed in  claim 1 , wherein the step of providing one or more cooling passages within the body comprises machining each of the cooling passages into the body from a first side of the body to a second, opposite side of the body. 
     
     
       3. The method as claimed in  claim 1 , wherein the step of providing one or more cooling passages may comprise providing two cooling passages located on diametrically opposed sides of the flapper of the SAFA. 
     
     
       4. The method as claimed in  claim 1 , wherein the torque motor comprises a pair of electromagnetic coils, and each of the one or more cooling passages is configured to direct the fluid between the pair of electromagnetic coils. 
     
     
       5. An apparatus comprising:
 a torque motor comprising: a spring, armature, flapper assembly (SAFA) comprising an armature configured to pivot about its center to cause a lower end of a flapper of the SAFA to move left and right; 
 a body, wherein the SAFA is mounted onto the body; and 
 a cap enclosing the SAFA; 
 wherein one or more cooling passages are provided within the body and are configured to receive a fluid and direct the fluid onto the SAFA of the torque motor; 
 wherein the body comprises a portion configured to receive the flapper of the SAFA, and the one or more cooling passages are configured to direct the fluid at least partially onto the portion configured to receive the flapper of the SAFA; 
 wherein the torque motor further comprises:
 a pole piece; 
 wherein each of the one or more cooling passages is configured to direct the fluid through an aperture formed in the center of the pole piece; 
 wherein each cooling passage comprises a central axis (X), and the central axis (X) of each cooling passage extends through the aperture of the pole piece. 
 
 
     
     
       6. The apparatus as claimed in  claim 5 , wherein the cap comprises a base and a sidewall extending from the base to a rim,
 wherein the rim is hermetically sealed against a surface of the body. 
 
     
     
       7. The apparatus as claimed in  claim 5 , wherein the cap defines an interior volume, the SAFA is located within the interior volume of the cap, and the cooling passages are configured to direct the fluid into the interior volume so as to cool one or more components of the SAFA located within the interior volume. 
     
     
       8. The apparatus as claimed in  claim 5 , wherein the one or more cooling passages includes at least two cooling passages located on diametrically opposed sides of the flapper of the SAFA. 
     
     
       9. The apparatus as claimed in  claim 5 , wherein:
 the pole piece is a substantially annular member comprising an outer radial surface and an inner radial surface; and 
 the inner radial surface defines the aperture and an outlet of each of the cooling passages is at least partially located radially inward of the inner radial surface. 
 
     
     
       10. The apparatus as claimed in  claim 5 , wherein the cooling passages are configured to direct the fluid onto a first side of the torque motor, the apparatus further comprising:
 a fluid outlet located on a second side of the torque motor, wherein the second side of the torque motor is opposite the first side of the torque motor, such that the fluid enters the torque motor on the first side thereof, and exits the torque motor on a second, opposite side thereof. 
 
     
     
       11. The apparatus as claimed in  claim 5 , wherein the torque motor comprises a pair of electromagnetic coils, and an outlet of each of the cooling passages is at least partially located between the pair of electromagnetic coils, such that fluid exiting each of the one or more cooling passages in use is directed between the pair of electromagnetic coils. 
     
     
       12. An apparatus as claimed in  claim 5 , wherein the torque motor comprises a pair of electromagnetic coils, and a volume is defined between the pair of electromagnetic coils, and each of the one or more cooling passages is configured to direct the fluid into the volume defined between the pair of electromagnetic coils.